A TCS Function Implementation Method Based on EPB

Abstract

This invention discloses a method for implementing TCS (Traction Control System) based on EPB (Electronic Braking Module), applied in the field of automotive braking technology. The method includes the following steps: inputting vehicle speed and wheel speed signals into the EPB's ECU; determining whether the vehicle is slipping based on the slip ratio; if slipping occurs, transferring the calculation results to a fuzzy PID algorithm to determine the degree of slip and calculate the adjustment torque; adjusting the torque by regulating the EMS throttle opening, and then re-judging the slip state; if the torque reaches a threshold and slip control is insufficient, feedback is sent to the ECU, which again calculates the required braking force using fuzzy PID and converts it into EPB current; the EPB controls the EPB current via an electrical signal to achieve braking and thus control slip. This invention utilizes brake pressure regulation and engine torque output intervention to implement TCS, gradually adjusting the actual slip ratio to approach the desired slip ratio, thereby improving the utilization rate of the EPB.

Description

Technical Field

[0001] This invention relates to the field of automotive braking technology, and more specifically to a method for implementing TCS function based on EPB. Background Technology

[0002] Electronic parking brake (EPB) systems have become increasingly common electronic braking systems. Characterized by electronically controlling the vehicle's brakes, EPB offers numerous advantages, such as precise brake force distribution, rapid response, and accurate control. Traction control system (TCS) is a technology used to improve vehicle stability on low-traction surfaces. In past development, TCS systems have typically been based on traditional hydraulic braking systems. Most existing TCS solutions rely on traditional PID algorithms, while alternatives employ more complex control algorithms and incorporate intelligent learning. However, these solutions often suffer from high complexity, computational burden, poor real-time performance, and may require higher costs and resource investment. Therefore, providing a method for implementing TCS functionality based on EPB is a crucial problem that needs to be solved by those skilled in the art. Summary of the Invention

[0003] In view of this, the present invention provides a TCS function implementation method based on EPB, which uses a fuzzy PID algorithm to calculate and process the wheel speed and vehicle speed data collected by the sensor, determines the vehicle slip state, calculates the torque adjustment value and the magnitude of the EPB current output to control the vehicle slip state, and determines the conditions for entering and exiting the TCS function, thereby achieving more efficient, accurate and reliable vehicle traction control.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for implementing TCS functionality based on EPB includes the following steps:

[0006] S1. Input the vehicle speed signal and wheel speed signal into the ECU of the EPB, and determine whether the vehicle is slipping by calculating the slip ratio;

[0007] S2. If slippage occurs, the calculation results are transferred to the fuzzy PID algorithm to determine the degree of slippage and calculate the amount of torque to be adjusted.

[0008] S3. The output torque is adjusted to the EMS. The torque is adjusted by adjusting the throttle opening of the EMS. After the torque adjustment is completed, the slip state is judged again.

[0009] S4. If the torque reaches the threshold and the slip control is insufficient, feedback is sent to the ECU, which calculates the required braking force again through fuzzy PID and converts it into EPB current.

[0010] S5 and EPB control the EPB current through electrical signals to achieve braking and control slippage. The slippage state and caliper working state are fed back to the ECU in real time to keep the slippage speed difference between the left and right drive wheels within a preset range.

[0011] Optionally, the slip ratio λ can be calculated as follows:

[0012]

[0013] In the formula, u is the vehicle speed, ω is the wheel rotation angular velocity, R1 is the wheel radius, and ωR1 represents the wheel speed. When the slip ratio λ is in the range of 12%-20%, it is judged that no slip has occurred; otherwise, it is judged that slip has occurred.

[0014] Optionally, the fuzzy PID algorithm specifically involves: using the difference between the target slip ratio S0 and the actual slip ratio S as the slip ratio error value e(t); fuzzifying the input variables to convert the specific input values ​​into fuzzy sets; performing fuzzy inference based on the fuzzy rule base and the fuzzy sets of the input variables to obtain the fuzzy output variable; and then, through defuzzification, converting the fuzzy output variable into a specific control quantity T. PID (t):

[0015]

[0016] In the formula, K p K is the proportionality coefficient. I K is the integration time constant. D is the differential time constant.

[0017] Optionally, the torque threshold in S4 can be calculated by using the dynamic equations to calculate the road surface adhesion coefficients on both sides of the drive wheel.

[0018]

[0019] In the formula, F Xmax The ground tangential reaction force, For adhesion, F z The normal reaction force on the ground, The adhesion coefficient;

[0020] The slope estimate is obtained by using longitudinal dynamic equations, time synchronization of control parameters, and hysteresis filtering of slope signals.

[0021] Calculate the maximum traction force F t :

[0022]

[0023] In the formula, F tWhere P is the maximum traction force, V is the engine power, f is the vehicle speed, R is the vehicle friction resistance, m is the vehicle mass, g is the acceleration due to gravity, and θ is the slope angle. The road surface adhesion coefficient;

[0024] Maximum threshold T of adjustable torque t for:

[0025] T t =F t Ri g i0η T

[0026] In the formula, i g For the transmission ratio, i0 is the gear ratio of the main reducer, and η is the gear ratio of the gearbox. T For the mechanical efficiency of the transmission system.

[0027] Alternatively, the longitudinal dynamic equation is:

[0028]

[0029] In the formula, T e For engine torque, i g For the transmission ratio, i0 is the gear ratio of the main reducer, and η is the gear ratio of the gearbox. T R is the mechanical efficiency of the transmission system, f is the wheel radius, f is the rolling resistance coefficient, and C is the rolling resistance coefficient. D Where A is the air resistance coefficient, v is the frontal area, and v is the air resistance coefficient. x Let m be the speed of the car, and a be the mass of the car. x For driving acceleration;

[0030] Control parameter time synchronization is as follows:

[0031]

[0032] The hysteresis filtering of the slope signal is as follows:

[0033]

[0034] The slope filter value obtained in the kth cycle. The slope filter value is obtained in the (k-1)th cycle, δ is the slope value increment, and Δ, S e To calculate the intermediate value, Q is the attenuation coefficient and ζ is the threshold value.

[0035] Optionally, the method for controlling slippage in S5 is as follows: the EPB current enters the MGU on the side of the high slippage drive wheel, and the piston is pushed by the mechanical transmission of gears and screw sleeves to make the friction plate contact the friction disc for braking. The clamping force of the caliper is controlled by the magnitude of the EPB current.

[0036] Optionally, after S5, it also includes:

[0037] S6. Modify the parameters in the fuzzy PID algorithm by continuously detecting the slip ratio error value and the rate of change of the slip ratio error value.

[0038] As can be seen from the above technical solution, compared with the prior art, the present invention provides a TCS function implementation method based on EPB, which has the following beneficial effects: The present invention utilizes brake pressure regulation and engine torque output intervention to realize the TCS function, which can gradually adjust the actual slip ratio to be close to the desired slip ratio, improve the utilization rate of EPB, enhance the functional development of EPB, improve the road surface adhesion utilization rate on open road surfaces, maintain the maneuverability of the drive wheels during driving, maintain the directional stability of the vehicle, and prevent the drive wheels from slipping easily when driving hard on low-adhesion surfaces; the present invention has the advantages of simplicity, reliability, strong real-time performance, and low cost, and is applicable to most rear-wheel drive vehicle chassis systems. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 This is a flowchart of the TCS function implementation method of the present invention;

[0041] Figure 2 This is a schematic diagram of the TCS function in the EPB of the present invention;

[0042] Figure 3 This is a schematic diagram of the fuzzy PID algorithm of the present invention;

[0043] Figure 4 This is a control feedback flowchart of the present invention;

[0044] Figure 5 This is a schematic diagram of the control feedback principle of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] This invention discloses a method for implementing TCS functionality based on EPB, such as... Figure 1 As shown, it includes the following steps:

[0047] S1. Input the vehicle speed signal and wheel speed signal into the ECU of the EPB, and determine whether the vehicle is slipping by calculating the slip ratio;

[0048] S2. If slippage occurs, the calculation results are transferred to the fuzzy PID algorithm to determine the degree of slippage and calculate the amount of torque to be adjusted.

[0049] S3. The output torque is adjusted to the EMS. The torque is adjusted by adjusting the throttle opening of the EMS. After the torque adjustment is completed, the slip state is judged again.

[0050] S4. If the torque reaches the threshold and the slip control is insufficient, feedback is sent to the ECU, which calculates the required braking force again through fuzzy PID and converts it into EPB current.

[0051] S5 and EPB control the EPB current through electrical signals to achieve braking and control slippage. The slippage state and caliper working state are fed back to the ECU in real time to keep the slippage speed difference between the left and right drive wheels within a preset range.

[0052] Furthermore, the slip ratio λ is calculated as follows:

[0053]

[0054] In the formula, u is the vehicle speed, ω is the wheel rotation angular velocity, R1 is the wheel radius, and ωR1 represents the wheel speed. When the slip ratio λ is in the range of 12%-20%, it is judged that no slip has occurred; otherwise, it is judged that slip has occurred.

[0055] Furthermore, such as Figure 3 As shown, the fuzzy PID algorithm specifically works as follows: The difference between the target slip ratio S0 and the actual slip ratio S is used as the slip ratio error value e(t). The input variables are fuzzified, converting the specific input values ​​into fuzzy sets. Based on the fuzzy rule base and the fuzzy sets of the input variables, fuzzy inference is performed to obtain the fuzzy output variable. Through defuzzification, the fuzzy output variable is converted into a specific control quantity T. PID (t):

[0056]

[0057] In the formula, K p K is the proportionality coefficient. I K is the integration time constant. D is the differential time constant.

[0058] Furthermore, the torque threshold in S4 is calculated using the dynamic equations to determine the road surface adhesion coefficients on both sides of the drive wheel.

[0059]

[0060] In the formula, F Xmax The ground tangential reaction force, F is the adhesion force, and Fz is the normal reaction force of the ground. The adhesion coefficient;

[0061] The slope estimate is obtained by using longitudinal dynamic equations, time synchronization of control parameters, and hysteresis filtering of slope signals.

[0062] Calculate the maximum traction force F t :

[0063]

[0064] In the formula, F t Where P is the maximum traction force, V is the engine power, f is the vehicle speed, R is the vehicle friction resistance, m is the vehicle mass, g is the acceleration due to gravity, and θ is the slope angle. The road surface adhesion coefficient;

[0065] Maximum threshold T of adjustable torque t for:

[0066] T t =F t Ri g i0η T

[0067] In the formula, i g For the transmission ratio, i0 is the gear ratio of the main reducer, and η is the gear ratio of the gearbox. T For the mechanical efficiency of the transmission system.

[0068] Furthermore, the longitudinal dynamic equation is:

[0069]

[0070] In the formula, T e For engine torque, i g For the transmission ratio, i0 is the gear ratio of the main reducer, and η is the gear ratio of the gearbox. T R is the mechanical efficiency of the transmission system, f is the wheel radius, f is the rolling resistance coefficient, and C is the rolling resistance coefficient. D Where A is the air resistance coefficient, v is the frontal area, and v is the air resistance coefficient. x Let m be the speed of the car, and a be the mass of the car. x For driving acceleration;

[0071] Control parameter time synchronization is as follows:

[0072]

[0073] The hysteresis filtering of the slope signal is as follows:

[0074]

[0075] The slope filter value obtained in the kth cycle. The slope filter value is obtained in the (k-1)th cycle, δ is the slope value increment, and α, S e To calculate the intermediate value, Q is the attenuation coefficient and ζ is the threshold value.

[0076] Furthermore, the method for controlling slippage in S5 is as follows: the EPB current enters the MGU on the side of the high slippage drive wheel, and the piston is pushed by the mechanical transmission of gears and screw sleeves to make the friction plate contact the friction disc for braking. The clamping force of the caliper is controlled by the magnitude of the EPB current.

[0077] Furthermore, after S5, it also includes:

[0078] S6. By continuously detecting the slip ratio error value and the rate of change of the slip ratio error value, the parameters in the fuzzy PID algorithm are modified. The feedback process and principle are as follows: Figure 4 and Figure 5 As shown.

[0079] In this embodiment of the invention, if the torque and EPB current are controlled to achieve the TCS function, after the control is completed, it is determined whether the target slip ratio requirement has been met. If the requirement is met, data is continuously collected to provide feedback on the slip state and the working state of the brake caliper, thereby continuously adjusting the torque and EPB current to ensure that the slip ratio difference between the left and right drive wheels is maintained within a reasonable range. If the target slip ratio requirement is not met, the parameters in the fuzzy PID algorithm need to be adjusted, and the torque and EPB current need to be recalculated to make the slip ratio closer to the target slip ratio.

[0080] Furthermore, in one embodiment of the invention, the TCS function employs a torque intervention request condition:

[0081] 1. Throttle opening exceeds the minimum threshold (3%);

[0082] 2. No braking signal;

[0083] 3. The deviation between the vehicle speed and the sum of the skid speeds reaches the set threshold. The threshold is considered to have been reached if any of the following conditions are met: the vehicle speed is less than 10 km / h and the deviation of the sum of the skid speeds is less than -5 km / h; the vehicle speed is less than 20 km / h and the deviation of the sum of the skid speeds is less than -4 km / h; the vehicle speed is less than 20 km / h and the deviation of the sum of the skid speeds is less than -3 km / h.

[0084] TCS function EPB braking intervention request conditions:

[0085] 1. Throttle opening exceeds the minimum threshold (3%);

[0086] 2. No braking signal;

[0087] 3. The threshold is considered to be reached if any of the following conditions are met: insufficient torque to compensate for pressure; slip speed difference exceeds the threshold value and the rate of change of slip speed difference exceeds the threshold.

[0088] TCS function torque exit request conditions:

[0089] 1. In torque control mode;

[0090] 2. No TCS inbound request;

[0091] 3. The driver's desired torque is less than the torque requested by the TCS;

[0092] 4. The slip speed is less than the threshold value;

[0093] 5. The above conditions are met for four consecutive cycles.

[0094] TCS function EPB brake disengagement request conditions:

[0095] Meeting any one of the following conditions is sufficient:

[0096] 1. Throttle opening is below the minimum threshold (3%);

[0097] 2. There is a braking signal;

[0098] 3. The vehicle speed exceeds the set threshold (50km / h);

[0099] 4. The rear wheel speed is less than the front wheel speed.

[0100] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0101] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for implementing TCS functionality based on EPB, characterized in that, Includes the following steps: S1. Input the vehicle speed signal and wheel speed signal into the ECU of the EPB, and determine whether the vehicle is slipping by calculating the slip ratio; S2. If slippage occurs, the calculation results are transferred to the fuzzy PID algorithm to determine the degree of slippage and calculate the amount of torque to be adjusted. S3. The output torque is adjusted to the EMS. The torque is adjusted by adjusting the throttle opening of the EMS. After the torque adjustment is completed, the slip state is judged again. S4. If the torque reaches the threshold and the slip control is insufficient, feedback is sent to the ECU, which calculates the required braking force again through fuzzy PID and converts it into EPB current. S5 and EPB control the EPB current through electrical signals to achieve braking and control slippage. The slippage state and caliper working state are fed back to the ECU in real time to keep the slippage speed difference between the left and right drive wheels within a preset range.

2. The method for implementing TCS functionality based on EPB according to claim 1, characterized in that, The slip ratio λ is calculated as follows: In the formula, u is the vehicle speed, ω is the wheel rotation angular velocity, R1 is the wheel radius, and ωR1 represents the wheel speed. When the slip ratio λ is in the range of 12%-20%, it is judged that no slip has occurred; otherwise, it is judged that slip has occurred.

3. The method for implementing TCS functionality based on EPB according to claim 1, characterized in that, The fuzzy PID algorithm is as follows: The difference between the target slip ratio S0 and the actual slip ratio S is used as the slip ratio error value e(t). The input variables are fuzzified, converting the specific input values ​​into fuzzy sets. Fuzzy inference is performed based on the fuzzy rule base and the fuzzy sets of the input variables to obtain the fuzzy output variable. Finally, through defuzzification, the fuzzy output variable is converted into a specific control quantity T. PID (t): In the formula, K p K is the proportionality coefficient. I K is the integration time constant. D is the differential time constant.

4. The method for implementing TCS functionality based on EPB according to claim 1, characterized in that, The torque threshold in S4 is calculated using the dynamic equations to determine the road adhesion coefficients on both sides of the drive wheel. In the formula, F Xmax The ground tangential reaction force, For adhesion, F z The normal reaction force on the ground, The adhesion coefficient; The slope estimate is obtained by using longitudinal dynamic equations, time synchronization of control parameters, and hysteresis filtering of slope signals. Calculate the maximum traction force F t : In the formula, F t Where P is the maximum traction force, V is the engine power, f is the vehicle speed, R is the vehicle friction resistance, m is the vehicle mass, g is the acceleration due to gravity, and θ is the slope angle. The road surface adhesion coefficient; Maximum threshold T of adjustable torque t for: T t =F t Ri g i0η T In the formula, i g For the transmission ratio, i0 is the gear ratio of the main reducer, and η is the gear ratio of the gearbox. T For the mechanical efficiency of the transmission system.

5. The method for implementing TCS functionality based on EPB according to claim 4, characterized in that, The longitudinal dynamic equation is: In the formula, T e For engine torque, i g For the transmission ratio, i0 is the gear ratio of the main reducer, and η is the gear ratio of the gearbox. T R is the mechanical efficiency of the transmission system, f is the wheel radius, f is the rolling resistance coefficient, and C is the rolling resistance coefficient. D Where A is the air resistance coefficient, v is the frontal area, and v is the air resistance coefficient. x Where is the vehicle's speed, δ is the vehicle's rotational mass conversion factor, m is the vehicle's mass, and a x For driving acceleration; Control parameter time synchronization is as follows: The hysteresis filtering of the slope signal is as follows: In the formula, The slope filter value obtained in the kth cycle. The slope filter value is obtained in the (k-1)th cycle, δ is the slope value increment, and Δ, S e To calculate the intermediate value, Q is the attenuation coefficient and ζ is the threshold value.

6. The method for implementing TCS functionality based on EPB according to claim 1, characterized in that, The specific method for controlling slippage in S5 is as follows: EPB current enters the MGU on the side of the high slippage drive wheel, and the piston is pushed by the mechanical transmission of gears and screw sleeves to make the friction plate contact the friction disc for braking. The clamping force of the caliper is controlled by the magnitude of the EPB current.

7. The method for implementing TCS functionality based on EPB according to claim 1, characterized in that, Following S5 are: S6. By continuously detecting the slip ratio error value and the rate of change of the slip ratio error value, determine whether the target slip ratio has been achieved.

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